1. Field of the Invention
The present invention relates generally to the field of wave-table upgrade cards. More particularly, the present invention relates to the provision of a wave-table upgrade card for a baseboard having integrated audio capabilities and features.
2. Description of the Related Art
A computer system typically provides audio capabilities and features to the system through an add-in card that is separate and distinct from the baseboard/motherboard of the computer system. For example, an audio card that provides sound capabilities to a computer system is typically coupled to the computer system through a system bus. The audio card receives data signals, control signals, and power supply voltages through the system bus.
Audio cards/circuits are well-known in the computer industry and typically include circuitry to perform the following functions: 1) Analog to Digital (A to D) and Digital to Analog (D to A) conversion of sound; 2) FM (frequency modulation) synthesis; 3) a MIDI (Musical Instrument Digital Interface protocol) and joystick interface; 4) decoding data from the system bus; and 5) mixer functions (i.e., mixing a number of sounds from different sources).
Initially, sound capabilities and features in a computer system were based entirely on FM synthesis. This technology generates different sounds by modulating sine waves. This technique is truly a "synthesis" in that one begins without any pre-recorded sounds. The starting point of FM synthesis is the selection of a single sine wave of a predetermined frequency (i.e., a pure tone). The sine wave at the preselected frequency produces a pure tone. One then uses another sine wave at a higher frequency to modulate the pure-tone sine wave. By so doing, a number of different notes and sounds may be created.
As technology for the digital sampling of sounds improved, the creation of sound through wave-table synthesis emerged as a technique for producing more true-to-life sounds. This wave-table technology is based on sampling different instruments and/or notes and storing these digitally sampled sounds into a memory. By using these stored sounds as a "library" of sounds, a dedicated signal processor is used to extrapolate and create any sound or note of an instrument from this library. This "library" of reference sounds enables the wave-table technology to produce more true-to-life sounds. Thus, when sound quality is important to an application, game, or multimedia presentation, wave-table technology is preferred over FM synthesis.
When this wave-table technology was initially implemented in a computer system, it was in the form of a stand-alone wave-table card. The card is coupled to the computer system through a system bus having a protocol such as ISA (Industry Standard Architecture). The card, which plugs into an ISA slot, would decode address, data and control signals from the ISA bus, reading and writing data from the bus. The card would also provide wave-table features and capabilities to the computer system would send the wave-table-synthesized audio to a jack in the back panel.
It is important to note that the wave-table upgrade card does not provide any of the audio features mentioned previously. Typically, these audio features were provided by a separate audio card that was coupled to another ISA slot.
There are four major disadvantages with implementing a wave-table card in a computer system by directly coupling the card to the system bus. First, since the wave-table card requires a capability to decode information from the ISA bus, additional circuitry is necessary to provide the necessary bus decoder logic. This logic increases the complexity and size (i.e., number of chips on the card) of the wave-table card. As card size and complexity increases, the cost to manufacture and produce the card increases proportionally.
Moreover, in this implementation the output of a wave-table card is separate and distinct from the output of the audio card. Thus, if a user of a computer system wanted to switch from an FM synthesis to a wave-table sound synthesis, the computer user would be required to physically reconfigure and reconnect speaker cables from one set of outputs to the other. This switching of speaker cables from the audio output jacks to the wave-table output jacks was very inconvenient and thus, a non-optimal solution.
In a second implementation of a wave-table card upgrade, the wave-table upgrade card is not directly coupled to the computer system through an ISA slot. Instead, the wave-table upgrade card is physically bolted and electrically coupled to a standard audio card. In other words, the wave-table card upgrade "piggy backs" on the standard audio card.
The audio card itself is physically and electrically coupled to the computer system through a bus slot of the ISA bus. The audio car d provides circuitry to decode information from the bus. Thus, the wave-table card is simplified because the wave-table card need not provide any bus decoder logic. Furthermore, the wave-table card used in this implementation is more cost efficient than the card in the first implementation. This implementation also saves an ISA slot since only one ISA slot is required in this implementation as compared to two ISA slots in the first implementation. This second implementation also obviates the manual switching of speaker cables from audio to wave-table outputs by providing an internal electric switching mechanism.
However, this second implementation still has several disadvantages. First, since the wave-table upgrade card is physically bolted to the audio card at specified mounting locations on the audio card, a wave-table upgrade card has to be of a predetermined/fixed size. Even if a manufacturer of a wave-table upgrade card could minimize logic and/or circuitry on the upgrade card, the actual fiberglass used must be a predetermined and fixed size since these dimensions are required to enable a physical coupling to the standard audio card. Second, the connector used to electrically couple the wave-table upgrade card to the standard audio card requires a high pin count, because all power and ground requirements must be supplied through the connector. These two factors, the fixed size of a wave-table upgrade card and the high pin count on the connectors, lead to an increase in the cost to manufacture the wave-table upgrade card and an increase in the cost of the connectors used to physically couple the audio card to the wave-table upgrade card.
In the two implementations discussed up to this point, an audio card that is separate and distinct from the baseboard provides the audio features of the computer system. When one integrates the audio features into a baseboard, the second implementation of a wave-table upgrade to an audio card is not possible because space constraints on the baseboard preclude mounting a wave-table card directly to the baseboard (i.e., a wave-table upgrade card cannot physically "piggy back" onto the motherboard).
Thus, a cost-efficient solution method and apparatus for providing a wave-table upgrade card to a baseboard with integrated audio capabilities is desirable.